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DTC P1031: ELC.Parking lock system fail
 
 
cautionBefore replacing the ECU, ensure that the communication circuit is normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets this DTC when the electric parking lock system fails.
 
 
 
PROBABLE CAUSES
  • Damaged harness or connector.
  • Malfunction of the electrical parking relay (stuck OFF).
  • The electric parking actuator fails (any of U, V, W phases stuck on or off).
  • The electric parking driver unit fails (internal error).
  • Malfunction of the PHEV-ECU.
 
 
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Using scan tool (M.U.T.-IIISE), check the data list (Electrical parking driver unit).
Check that the following data list display contents are normal (Refer to GROUP 22A - Electrical Parking Driver Unit, Data List Reference Table ).
Data list
  • Item No.6: Motor all-phase fail flag
  • Item No.7: Motor one-phase fail flag
  • Item No.17: ECU fail flag
 
Check conditionNormal condition
The parking lock statusNormalOFF
AbnormalON
Is the check result normal?
Go to Step 11.
Go to Step 2.
 
STEP 2. Check electrical parking relay.
Refer to GROUP 22A - Electrical Parking Relay Check .
Is the check result normal?
Go to Step 3.
Replace the electrical parking relay.
 
STEP 3. Voltage measurement at the electrical parking relay connector.
(1) Remove the electric parking relay, and measure at the relay box side.
(2) Measure the voltage between terminals No.3, No.4 and body ground.
OK: Approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 5.
Go to Step 4.
 
STEP 4. Check the power supply line for open circuit and ground short circuit (fusible link 8 and the electrical parking relay).
Check the wiring harness fusible link 8 and electrical parking relay connector (terminals No.3, No.4).
Is the check result normal?
Go to Step 5.
Repair the connector or wiring harness.
 
STEP 5. Voltage measurement at the electrical parking driver unit connector
(1) Install the electric parking relay.
(2) Disconnect the electric parking driver unit connector and measure at the wiring harness side.
(3) Measure the voltage between terminal BMB and body ground
OK: Approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 7.
Go to Step 6.
 
STEP 6. Check the power supply line for open circuit and short to ground circuit (electrical parking relay and electrical parking driver unit).
Check the wiring harness electrical parking relay connector (terminal No.1) and electrical parking driver unit connector (terminal BMB).
Is the check result normal?
Go to Step 7.
Repair the connector or wiring harness.
 
STEP 7. Check the power supply line for open circuit and short to ground circuit (electrical parking actuator and electrical parking relay).
Check the wiring harness electrical parking actuator connector (terminal No.4) and electrical parking relay connector (terminal No.2).
Is the check result normal?
Go to Step 8.
Repair the connector or wiring harness.
 
STEP 8. Check the signal line for open circuit and short to ground circuit (electrical parking actuator and electrical parking driver unit).
Check the wiring harness electrical parking actuator connector (terminals No.5, No.10, No.9) and electrical parking driver unit connector (terminals MBU, MBV, MBW).
Is the check result normal?
Go to Step 9.
Repair the connector or wiring harness.
 
STEP 9. Check electrical parking actuator.
Refer to GROUP 22A - Inspection .
Is the check result normal?
Go to Step 10.
Replace the electrical parking actuator (Refer to GROUP 22A - Electrical Parking Actuator ).
 
STEP 10. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
Replace the electrical parking driver unit (Refer to GROUP 22A - Electrical Parking Drive Unit ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 11. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).